As it transpires, I have a little problem with my adventure map. See, I wanted to make it hard enough to be challenging to play through in a group. I don't know how well I succeeded, but I've definitely made it too difficult to play through solo (at least for a wimpy incompetent player like yours truly). Which is a problem, because now Havoc's said he's not restoring the End, I need to get into the Exposition Room to change said Exposition. And since I can't use creative mode, I can't get there...
I'd also like to adapt some of the traps to include new features like the way dispensers now interact with lava, and maybe use a book for exposition instead of walls of signs. Also last time I checked it right before I went away I found that mobs had damaged some of the traps and signs (endermen moving gravel, mobs setting off pressure pads and so on) and I would really like to ensure that my previous attempts to fix the issues have worked. But as I say this is all moot because I can't get down there. What I'm wrangling towards is to request that Havoc restore Creative to me for a few hours so I can make the required changes.
Please?
If I can make the required fixes very soon, I'll run the event this Saturday.
Also, I lost the chest full of reward goodies when the End was broken, so there won't actually be any rewards for the adventure.